xml DOM/DTD graph visualization

[james anderson <james.anderson@setf.de>]

I was curious about how an automatic layout package would fare with DTD
and DOM graphs. A naive generator for GraphViz's "dot" format is a
straight-forward graph walk. The "dot" file describes the connectivity
only. GraphViz is left with the hard work. The results are adequate for
smaller examples[0], but larger instances will need a more refined approach.

The larger files failed to load with the current GraphViz 1.7.6 beta for
Windows. As I'm rather Linux/C imparied, I was fortunate and grateful,
that someone was curious and ran them through the Linux version. Thus
the two SVGs below, which I was able to view with Adobe's SVG plugin. 

REC-xml-20001006.xml: DTD as DOT[1], as SVG[2]
REC-xhtml1-20000126.html: DTD as DOT[3], as SVG[4]

They tend to tax this viewers patience and perspicacity. Which leads to
the questions:

When one is "visualizing" a DOM or a DTD, which relations is one
"looking" for?
- direct neighbors to a given element/attribute or element type definition?
- direct siblings?
- a vertical sub-graph comprising a specified node subset?
- a vertical sub-graph ...?
- nodes in the same namespace?
- some other partition?

How would one wish to describe what one is "looking" for.
- a collection of names?
- a path expression?

Anyone curious about DOCBOOK?

...

[0] http://homepage.mac.com/james_anderson/XML/index.html
[1] http://homepage.mac.com/james_anderson/XML/Graphs/xmlSpec.dot
[2] http://homepage.mac.com/james_anderson/XML/Graphs/xmlSpec.svg (768K)
[3] http://homepage.mac.com/james_anderson/XML/Graphs/xhtmlHtml.dot
[4] http://homepage.mac.com/james_anderson/XML/Graphs/xhtmlHtml.svg (444K)

ps. I don't know how to get the server to specify the correct mime type.
It serves the SVGs up as text/plain, so one may need to download them
separate from viewing.